(Picture by Alexander Gerst from the ISS)
We take good old O2 for granted. People are always going on about how early Earth was “perfect” for life. A perfect hell maybe. No ozone layer, no oxygen, extreme heat, an abundance of highly corrosive chemicals in the atmosphere including sulfur and methane.
Much like found on Titan the largest of the moons of Jupiter today. It was a literal red sky hell. With all of that methane and sulfur, it must have smelled like a frat house on chili and hard boiled egg night. So, the Earth was devoid of oxygen in the beginning but as I said there was a metric butt-load of methane and sulfur in the oceans.
So, little single-celled organisms developed that lived on methane and sulfur. After a while, the sulfur level dropped and the methane level did as well. No one is sure why. There still was little oxygen. So some more little critters evolved which produced oxygen called “cyanobacteria”.
It took a billion years for these critters to terraform our planet for the evolution of animals and more complex plants. To this day all plants incorporate these ancient cyanobacteria into their cells in structures known as a “cyanoplasts”. You see life itself changed the planet to support life.
This is what life does.
More informations to this topic: https://en.wikipedia.org/wiki/Great_Oxygenation_Event
#Science #Enviroment #Universe #Earth #Life